Method of making oil control piston rings

ABSTRACT

A method of making oil control piston rings having inner diameter and outer diameter central channels with oil drainage slots spaced apart circumferentially communicating the channels, the outer diameter having axially spaced apart scraping beads with radial grooves therein filled with a hard facing metal. The method includes the sequential steps of making a cast unsplit ring, providing axially spaced-apart radial grooves in the outer diameter of the ring, providing an internal inner diameter channel in the said ring, forming blind oil drainage slots in the inner diameter of the ring, spray-coating stacked rings on the outer diameter with a hard-faced coating, machining the stacked rings on the outer diameter to remove the coating except in the area of the outer diameter grooves, forming an outer diameter channel on the ring thereby opening the blind oil slots and forming bevels on the axial ends of the outer diameter of the ring and thereafter splitting the ring axially.

United States Patent Prasse METHOD OF MAKING OIL CONTROL PISTON RINGS[72] Inventor: Herbert F. Prasse, Town & Country,

[73] Assignee: Ramsey Corporation, St. Louis, Mo. [22] Filed: March 10,1971 [21] Appl. No.: 122,798

Primary Examiner-John F. Campbell Assistant Examiner-Victor A. DiPalmaAtt0rney-Hi1l, Sherman, Meroni, Gross & Simpson [57] ABSTRACT A methodof making oil control piston rings having inner diameter and outerdiameter central channels with oil drainage slots spaced apartcircumferentially communicating the channels, the outer diameter havingaxially spaced apart scraping beads with radial grooves therein filledwith a hard facing metal. The method includes the sequential steps ofmaking a cast unsplit ring, providing axially spaced-apart radialgrooves in the outer diameter of the ring, providing an internal innerdiameter channel in the said ring, forming blind oil drainage slots inthe inner diameter of the ring, spray-coating stacked rings on the outerdiameter with a hard-faced coating, machining the stacked rings on theouter diameter to remove the coating except in the area of the outerdiameter grooves, forming an outer diameter channel on the :ring therebyopening the blind oil slots and forming bevels on the axial ends of theouter' diameter of the ring and thereafter splitting the ring axially.

3 Claims, 20 Drawing Figures METHOD OF MAKING OIL CONTROL PISTON RINGSBACKGROUND OF THE INVENTION 1 Field of the Invention This inventionrelates to piston rings and more particularly to a method of forming anoil control piston ring.

2. Prior Art .It is known to employ an oil control ring between acylinder and a piston reciprocating therein, which ring engages thecylinder on both sides of a central radial channel and has slotstherethrough so that drainage can occur from the cylinder through thering and through conventional drainage or smoke holes in the piston tothe interior thereof.

Rings according to the present invention are onepiece slotted channeloil control rings having narrow peripheral bands of porous wearresistant metal applied thereto.

Such prior art rings are evidenced by the U. S. Pat. No. 3,435,502 toThompson et al. The prior art rings such as these are generallyconstructed of split ring blanks which are placed on an arbor and workedfrom the exterior thereof except for the forming of an inner channel.

The prior art manufacturing techniques used have numerous disadvantages,including the problems of proper spacing of the oil drainage slots on asplit ring, problems associated with weakening of the ring blank atvarious steps in the process and the disadvantageous necessity ofstacking and restacking rings on arbors.

SUMMARY OF THE INVENTION This invention overcomes these disadvantages byproviding a sequential method for the production of such rings whereinin the preferred embodiment, the rings are not split until after themajority of other operations has been performed thereon. This assuresring stability during the necessary machining and/or grindingoperations.

Additionally, the oil slots are provided from the inner diameter outwhich produces an advantageous ring design less susceptible to oilclogging than rings produced by prior methods.

The invention includes the sequential steps of providing a ring blank ofrectilinear cross-sectional configuration having inner and outerdiameter circumferential walls and axially spaced radially extending endwalls.

Thereafter, the following sequential operations are performed upon thering:

a. A pair of axially spaced-apart radially narrow grooves are formed inthe outer diameter;

b. A central inner diameter radially extending channel is formed in theinner diameter wall;

c. A plurality of circumferentially spaced radial slots are formed inthe inner diameter wall of the inner diameter groove, the slotsterminating within the material of the ring;

d. A wear-resistant facing is applied to the outer diameter of the ring;

e. The wear-resistant facing is ground off the outer diameter of thering except for the grooves;

f. An outer diameter radially extending axially centrally locatedchannel is formed, communicating to the oil drainage slots, and theaxial end outer diameter corners are bevelled;

g. The ring is split.

Steps (d) and (e) may be performed immediately after step (a) ifdesired. I

It is therefore an object of this invention to provide an improvedmethod for manufacturing an oil control ring.

It is another and more important object of this invention to provide animproved method of manufacturing an oil control ring having inner andouter diameter channels with circumferentially spaced oil drainage slotscommunicating with the channels, the slots formed from the innerdiameter of the ring.

It is yet another and more important object of this invention to providean oil control ring having outer diameter axially spaced-apart scrapingbeads with grooves of wear-resistant material therein, an inner diameterchannel and oil slots communicating the outer periphery to the innerdiameter, wherein the ring is produced from a ring blank, the ring blankhaving a plurality of operations performed thereon and the ring blankremaining unsplit until a majority of such operations are performed.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantagesof the invention will be readily apparent from the following descriptionof a preferred embodiment thereof, taken in conjunction with theaccompanying drawings, although variations and modifications may beeffected without departing from the spirit and scope of the novelconcepts of the disclosure, and in which:

FIG. I is a fragmentary cross-sectional view of a piston received in acylinder, the piston having a ring groove with an oil control ringformed according to a method of this invention;

FIG. 2 is a fragmentary top plan view of the oil control ring of thisinvention;

FIG. 3 is a plan view of the oil control ring of this invention;

FIG. 4 is a fragmentary diagrammatic view of the grooving operation inthe method of this invention;

FIG. 5 is a fragmentary diagrammatic view of the inner diameter channelforming operation of the method of this invention;

FIG. 5a is a fragmentary diagrammatic view of the slot forming operationof the method of this invention;

FIG. 6 is a fragmentary cross-sectional view of a ring produced afterthe step illustrated in FIG. 5;

FIG. 7 is a planview of a plurality of rings received on an arbor priorto the operations illustrated in FIGS. 8 and 9;

FIG. 8 is a fragmentary diagrammatic cross-sectional view of the coatingoperation of this invention;

FIG. 9 is a fragmentary view similar to FIG. 8 illustrating the facingremoval operation of this invention;

FIG. 10 is a fragmentary diagrammatic view of the outer channel andbevel forming operation of this invention;

FIG. 11 is a cross-sectional fragmentary view of a ring producedaccording to the method of this invention after the step of FIG. 10;

FIGS. 12 through 18 are fragmentary cross-sectional views of a ringproduced according to the teachings of this invention illustrating theindividual steps performed thereon.

FIG. 19 is a diagrammatic view illustrating the ring splittingoperation.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates an oilcontrol ring received in the oil ring groove 11 of a piston 12 receivedin a cylinder 13 of an engine. The piston 12 has an oil drainage andsmoke hole 14 communicating with the back of the groove 11 and theinterior of the piston.

The ring 10 has a pair of axially spaced-apart oil scraping beads 15formed by radially extending circumferential projections adjacent theaxial end walls 17 and 18 of the ring 10. The beads 15 havecircumferential grooves 19 therein filled with hard-facing metal 20. Thering 10 has an outer diameter central channel 21 formed as acircumferential recession in the outer diameter of the ring between thebeads 15. An inner diameter channel 22 is also provided and communicateswith the outer diameter channel 21 through a plurality ofcircumferentially spaced-apart oil drainage holes 23. A circumferentialexpander ring 24 is received in the groove 11 and has radiallyprojecting leg portions 25 received in the channel 22 and abutting theinner diameter wall 29 of the channel 22 axially beyond the oil slots23.

As illustrated in FIG. 2, the ring 10 is split at 30, providing gap ends31, thereby allowing the ring 10 to expand and contractcircumferentially, increasing or decreasing the gap 30. In the preferredembodiment, the outer peripheral axial corners 34 of the ring 10 arebevelled.

The ring 10 is constructed according to the method of this invention.First, a ring blank, as illustrated in FIG. 12, is provided. The blank35 is ring-shaped, having in cross section an outer diameter wall 36, aninner diameter wall 37 and axial end walls 17 and 18. The axial endwalls 17 and 18 are radial. The first step normally performed on thering blank is to machine the axial end walls 17 and 18 to the desiredradiality and to machine the ring to the desired width.

Thereafter, the ring blank 35 is placed in a single ring turning machinesuch as is illustrated in FIG. 4. The single ring turning machineincludes a hollow-shafted member 40 received in a housing 41 in relativerotation therewith through a bearing assembly 42. One end 43 of thehollow shafted member 40 has a radial wall 44 which contacts an axialend wall 17 of the ring blank 35. A rotatable drive member 45 pressesagainst the other axial end 18 of the ring blank 35 and rotates the ringwith respect to the housing 41. Thus, the ring blank 35 is enclampedbetween the drive member 45 and the hollow shafted member 40 and rotatestherewith. The ring blank 35 is accessible to tools on the outer or theinner diameter. Inasmuch as the ring blank 35 is unsplit during theperformance of the operation illustrated in FIG. 4 and other figuresutilizing the single ring turning machine, such tools may work on theinner or outer diameter of the ring blank without fear ofcircumferential collapse of any portion of the ring such as could beencountered with a split ring where the gap at the split could decreaseduring operation of a tool on either the inner or outer diameterthereof, thereby adversely affecting the operation being performed onthe ring.

After machining the ring to size to produce the blank illustrated inFIG. 12, the ring is inserted in the single ring turning machine and thecircumferential outer diameter grooves 19 are formed. As illustrated inFIG. 4, they may be formed by a double headed tool 46 which has a pairof axially spaced-apart machining edges 47 and 48 projecting therefrom.The machining edges 47 and 48 preferably have an axial thicknessdimensioned to provide a groove of the desired thickness in an axialdirection. The tool is radially movable with respect to the hollowsleeve 40 of the turning machine to cut the grooves to the desiredradial depth. The grooves 19 are axially spaced apart and are formed agiven distance from the axial ends 17 and 18 of the ring blank. 7

Next, as illustrated in FIGS. 5 and 14, a cutting tool 50 is insertedinto the single ring turning machine from the interior thereof. Thecutting tool 50 has a cutting head 51 dimensioned to cut the innerdiameter channel 22 into the inner diameter wall 37 of the ring blank35. The inner diameter channel'22 is centrally positioned between theends 17 and 18 of the ring blank 35, leaving radially inwardly directedlands 52 and 53 defining the axial ends of the channel 22 and an axialperipheral wall 29 at the bottom of the channel.

Next, as illustrated in FIGS. 5a and 15, the oil drainage slots 23 areformed from the inner diameter wall 29 of the groove 22 into thematerial of the ring blank 35. For this operation, the ring blanks 35may be removed from the single ring turning machine and stacked in acup-shaped arbor 60 in end-to-end relation as illustrated in FIG. 5a. Insuch a case, the oil drainage slots 23 may be formed by a multi-headedtool 61 which extends into the inner diameter of the cupshaped arbor 60and which has a plurality of cutting or machining heads 62 thereon whichhave a diameter smaller than the diameter of the ring. The axis of thetool 61 is movable and is positioned off-center from the axis of thearbor 60 whereby the slots 23 are arcuately cut into the material of thering 35, each slot, as illustrated in FIG. 6, being deeper into thematerial of the ring body 35 at its centerpoint 63 than at itscircumferential end 64. In a preferred embodiment, the tool heads 62 aretapered to form a wedge shaped slot whereby all of the walls of the slotdiverge from the outer side of the ring to the inner side. The slots 23are cut a given depth into the material of the ring body 35 withoutbreaking through the outer periphery 36 thereof. Thus, initially the oildrainage slots 23 are formed blind, open only to the inner diameter ofthe ring. The slots 23 are preferably axially narrower than the channel22, and are centered on the bottom wall 29 of the channel, therebyproviding axial ledge faces on the bottom wall 29 of the channel 22 forabutment with the expander 24.

Next, the rings 35 are placed upon an arbor in stacked relation asillustrated in FIG. 7. The arbor comprises a mandrel 71, an enlargedshoulder 72 integral with one end of the mandrel, a cap 73 at the otherend of the mandrel, a bolt 74 having an enlarged head 75 and a nut 76threaded onto the bolt. The stack of ring blanks 35 fits over themandrel 71 and is enclamped between the shoulder 72 and the cap 73 bymeans of the bolt 74 and nut 76, the bolt going through the mandrel 71,the bolt headengagingthe shoulder 72 and the nut engaging. the cap 73.The ends of the .bolt 74 have suitable-indentations 77 and 78 whichfacilitate mounting thearbor 71, on suitable driving means (not I In thepreferred embodiment, the blanks are coated by flame spraying from aflamespray apparatus 81 to'a depth sufficient to adequately coat all oftherings thereby assuring depositation of the material 80 in the grooves19. During the spraying operation, the arbor 71 may be rotated. Afterflame spraying, the rings on the arbor are next subjected to a machiningwheel 83 best illustrated in FIG. 9. The wheel 83 is applied to theexterior of the stack of ring blanks 35 so that the excess of the flamesprayed material 80 is removed and such metal is left only in thegrooves 19, thereby providing the facing 20 in the grooves 19 asillustrated in FIG. 1.

Next, the rings are removed from the arbor and returned to the singlering turning machine as illustrated in FIG. where they are engaged by atool 90 having a cutting or machining face 91 with two bevelled grooves92 therein aligned with the grooves 19 of the ring blank 35. The cuttingor machining tool 90 is then used to form the outer diameter channel 21centrally in the outer diameter of the ring, thereby providt ing thescraping beads at either end of the channel. Further, the axially outersides 94 of the grooves 92 in the tool form bevelled edges 34 on theaxially outer ends of the scraping beads.

The formation of the channel 21 breaks through to the bottom of the oildrainage slots 23 thereby communicating the slots 23 to the channel 21at least over a portion of the central portion of the slots 23 as isbest illustrated in FIG. 11. The central portion of the slots 23 areeach open to the outer diameter of the channel while the entirety of theslots 23 are open to the inner diameter channel 22. In this manner, theslots increase in size from the outer diameter to the inner diameter,thereby providing better oil flow. In prior art rings where the slotshave been formed from the outer diameter rather than from the innerdiameter, the slots have decreased in area from the outer to the innerdiameter, thereby allowing buildup of sludge and restricted flow.

Next, the ring blanks 35 are slotted as by a cutting tool 100diagrammatically illustrated in FIG. 19. The slots are dimensioned so asto provide the desired gap 32. It will be appreciated that at thispoint, a completed oil control ring is formed which may, if desired, besubjected to further operations such as deburring, polishing and/orphosphate coating.

Where it is desired to introduce the ring to the single ring turningmachine with the same alignment in each step, an identification pip ormark may be placed on one of the faces 17 or 18 at or prior to thegrooving operation illustrated in FIG. 1. The pip will then serve toidentify one side of the ring for introduction into the machine and mayfurther serve to identify the top of the ring for installation in thering groove.

It will therefore be appreciated that my invention illustrates a methodof producing an oil control ring having inner and outer diameterchannels communicated by oil slots whose walls diverge from the outer tothe inner diameter, the outer periphery of the ring having axiallyspaced-apart scraping beads at the axial ends of the outer channel, thebeads having hard facing metal filled grooves therein.

It is essential to my invention that the inner diameter channel and theoil slots *be formed prior to the outer diameter channel; In thismanner, the oil slots are always formed blind into the materialof thering blank, and thereafter are open during formation of the outerchanneL'If desired, the application of the facing metal andthe machiningof the facing metal may be accomplished prior to formation of the innerdiameter channel and the blind oil drainage slots. However, facing andmachining of the facing should always be done prior to formation of theouter diameter channel. It is further essential to my invention that thering blanks remain unsplit at least until after the completion of allinner diameter cutting and grinding operations. It is preferable thatthe ring remain unsplit until after the outer diameter channel has beenformed, breaking through to the oil drainage slots. It will beappreciated that by maintaining the ring in an unsplit condition,formation of the oil drainage slots is simplified. In priorartembodiments where the ring was split as an initial step or prior to theformation of the oil drainage slots, it was necessary to specificallyalign the ring blanks with respect to the tool used to form the oildrainage slots so that the slots were not formed in the area of the gap.By splitting the ring after the slots have been formed, it is relativelysimple to cut the ring at a point between adjacent slots, therebymaintaining the strength of the ring at the gap.

Although I have herein set forth my invention with respect to certainspecific principles and details thereof, it will be understood thatthese may be varied without departing from the spirit and scope of theinvention as set forth in the hereunto appended claims.

I claim as my invention:

1. The method of making an oil control ring from an unsplit ring blankcomprising the sequential steps of: forming two peripheral grooves inthe periphery of the blank, then cutting an interior channel in theinner periphery of the blank, then machining a plurality of slots fromthe interior of the channel radially outward without communicating theslots to the outer periphery of the blank, then coating the exterior ofthe blank with porous wear-resisting metal filling the said grooves withthe said metal, then machining away the metal coating to remove it fromthe ungrooved portions of the periphery, leaving the grooves filled withmetal, then cutting an outer diameter central radially extending channelinto the periphery of the ring, the bottom of said channel communicatingwith the saidslots, and forming bevelled edges at the axial ends of theouter periphery, and then cutting through the ring axially to split it.

2. The method of making an oil control ring comprising the steps of,first, forming an unsplit ring blank having inner and outer diametersand axial end walls, then forming axially spaced-apart radial grooves inthe outer diameter of said ring in a single ring turning machine, thenforming an inner diameter channel radially outwardly from the innerperiphery of said ring in a single 7 ring turning machine, then forminga plurality of circumferentially spaceddapart radius bend slots in thesaid ring radially outwardly from the inner diameter of the said innerdiameter groove, the said slots being formed blind and not communicatingto the outer diameter, then coating the outer diameter of the said ringwith a facing metal filling the said grooves, then removing the saidfacing metal from the said outer diameter except in the said grooves,then forming an outer diameter channel radially inwardly in the saidring communicating with the said slots, the said outer diameter channelbeing formed intermediate the said outer diameter grooves, then axiallysplitting the said 3. In the method of making an oil control ring whichhas inner and outer diameter circumferential channels communicated by aplurality of circumferentially spaced-apart oil drainage slots, theimprovement of forming the inner diameter channel first, forming the oildrainage slots blind into the material of the ring, the slots increasingin size towards the inner diameter and thereafter forming the outerdiameter channel to a depth sufficient to communicate to the bottom ofthe slots, the ring blank remaining unsplit at least until afterformation of the blind oil drainage slots.

1. The method of making an oil control ring from an unsplit ring blankcomprising the sequential steps of: forming two peripheral grooves inthe periphery of the blank, then cutTing an interior channel in theinner periphery of the blank, then machining a plurality of slots fromthe interior of the channel radially outward without communicating theslots to the outer periphery of the blank, then coating the exterior ofthe blank with porous wear-resisting metal filling the said grooves withthe said metal, then machining away the metal coating to remove it fromthe ungrooved portions of the periphery, leaving the grooves filled withmetal, then cutting an outer diameter central radially extending channelinto the periphery of the ring, the bottom of said channel communicatingwith the said slots, and forming bevelled edges at the axial ends of theouter periphery, and then cutting through the ring axially to split it.2. The method of making an oil control ring comprising the steps of,first, forming an unsplit ring blank having inner and outer diametersand axial end walls, then forming axially spaced-apart radial grooves inthe outer diameter of said ring in a single ring turning machine, thenforming an inner diameter channel radially outwardly from the innerperiphery of said ring in a single ring turning machine, then forming aplurality of circumferentially spaced-apart radius bend slots in thesaid ring radially outwardly from the inner diameter of the said innerdiameter groove, the said slots being formed blind and not communicatingto the outer diameter, then coating the outer diameter of the said ringwith a facing metal filling the said grooves, then removing the saidfacing metal from the said outer diameter except in the said grooves,then forming an outer diameter channel radially inwardly in the saidring communicating with the said slots, the said outer diameter channelbeing formed intermediate the said outer diameter grooves, then axiallysplitting the said ring.
 3. In the method of making an oil control ringwhich has inner and outer diameter circumferential channels communicatedby a plurality of circumferentially spaced-apart oil drainage slots, theimprovement of forming the inner diameter channel first, forming the oildrainage slots blind into the material of the ring, the slots increasingin size towards the inner diameter and thereafter forming the outerdiameter channel to a depth sufficient to communicate to the bottom ofthe slots, the ring blank remaining unsplit at least until afterformation of the blind oil drainage slots.